Interpretive Summary: Ecosystems that have been modified by humans to produce food, fiber or other agricultural products are known as agroecosystems. Issues such as food safety, environmental degradation, and the decline of the family farm have contributed toward the broadening of agriculture's scope beyond a focus on production. The concept of agroecosystem captures this broader scope as agroecosystems are derived from the interaction of environmental, socioeconomic and cultural factors that define human food and fiber production systems. As a relatively new science, agroecology seeks to integrate agricultural and ecological disciplines and contribute to knowledge needed for addressing complex agricultural issues and developing sustainable agroecosystems. Concepts of holism, hierarchy, emergent properties, transformation, control, and communication are fundamental to systems theory. These premises of agroecosystems provide a framework for comparing natural ecosystems to agroecosystems. Driving variables that affect ecosystem structure and function are defined as determinants. Major ecological determinants consist of climate, organisms, parent material (geologic substrate) and topography that operate over time to create agroecosystem properties and drive processes. In agroecosystems, this concept has been expanded to add human socioeconomic factors (e.g. land, labor, capital, management goals and capabilities) to ecological determinants. Agroecosystem determinants are integrated by farmers to guide decisions regarding choice and application of cultural practices (e.g. cultivation, crop selection, planting, residue management, nutrient inputs, pesticide use, water management, fire, harvest) that shape agroecosystem structure and function to achieve performance goals.

Technical Abstract:
Ecosystems that have been modified by humans to produce food, fiber or other agricultural products are known as agroecosystems. Issues such as food safety, environmental degradation, and the decline of the family farm have contributed toward the broadening of agriculture's scope beyond a focus on production. In contrast to natural ecosystems, agroecosystems derive greater complexity from the interaction of environmental, socioeconomic and cultural factors that define human food and fiber production systems. As a relatively new science, agroecology seeks to integrate agricultural and ecological disciplines and contribute to knowledge needed for addressing complex agricultural issues and developing sustainable agroecosystems. Concepts of holism, hierarchy, emergent properties, transformation, control, and communication are fundamental to systems theory. These important premises of agroecosystems, provide a framework for comparing natural ecosystems to agroecosystems. Driving variables that affect ecosystem structure and function are defined as determinants. Major ecological determinants consist of climate, organisms, parent material (geologic substrate) and topography that operate over time to effect agroecosystem properties and processes. In agroecosystems, human socioeconomic factors (e.g. land, labor, capital, management goals and capabilities) are added to ecological determinants. Agroecosystem determinants are integrated by farmers to guide decisions regarding choice and application of cultural practices (e.g. cultivation, crop selection, planting, residue management, nutrient inputs, pesticide use, water management, fire, harvest) that shape agroecosystem structure and function to achieve performance goals.